The construction of modular housing is accomplished advantageously in a factory using mass production techniques. Heretofore, the assembly line began where separate floor and wall sections were joined together. Each of these floor and wall sections, however, was constructed through the use of stationary jigs and hand-operated pneumatic nailing guns. The various frame members employed to form a floor or wall section were placed by hand in cradles or guides formed on the jigs and were nailed together with the hand-operated guns. Sheeting material was then placed on the frame and fastened thereto before hoisting the resulting building component from the jig.
The amount of physical labor involved in the above-described process was substantial. Typically, the operator was required to manipulate frame members that were eight, twelve or twenty-four feet in length and that were nominally 2.times.8's or 2.times.4's. Many of these frame members were doubled together. Sheet material such as dry wall and plywood or particleboard ranging in size from 4.times.8 to 12.times.8 feet were employed. The hand operation of nail-driving guns was also quite tiring. The results of operator fatigue were low output, low product quality, and job dissatisfaction.
The closest prior art known to the inventors are U.S. Pats Nos. 3,688,965 to Kellner et al; 3,537,168 to Carroll; 3,873,015 to Whitaker; 3,968,560 to Vial; 4,305,538 to Schultz; 3,086,210 to Good et al and 3,592,376 to Moehlenpah. Each of the above-cited patents discloses automated equipment for forming various building components, particularly wall sections. However, the means of positioning the workpiece during the sequential operations has, heretofore, been a problem. The problem is particularly acute downstream of the frame-forming station, particularly where edge portions of two adjoining pieces of sheet material need to be positioned over a single frame member and secured in place by fasteners extending into the adjoining edges and the frame member.
The present invention automates substantially the entire floor assembly process, thereby defining a new beginning for the conventional housing module assembly line. In contrast to the above-cited prior art, the present invention provides a pair of workpiece indexing devices that carry the frame workpiece to a precise position where sheet material is placed and, thence, to a precise position on a sheet nailing device. Additional means for insuring that the sheet material is properly positioned and for holding the combined sheet material and workpiece frame in place while the nailing process are also provided.